967 



iVIoNTAGNK ') foniul soiiic yctirs a.uo llial a number of aromatic 

 ketones are already I'ethiccd h\ hoiliii^- willi alcoliolic potassium 

 liydroxide ; it is very well ])ossil)le tliat tlic strongly alkaline reaction 

 of the medium increases the aftinity of the ketone oxygen for the 

 livdrogcii of the alcohol luoloculcs, so that also hei'e half |tinacoue 

 mols. are formed'') as follows: 



2 (C«H,), C-0 + CJI„() = C^H.O + 2 (C«HJ, OH etc. 



The phase of the entire i)inacone mols. is very rapidly gone through 

 in this case. 



It si)eaks for itself that this jxnverful alllinity influence of the 

 medium will also make its action felt on other bonds in the molecule, 

 so that the entire phenylgrouj) may be resolved or halogen atoms 

 become "activated" as found by Montagnk, an action that ceases, or 

 becomes less, when the entire C = O-group is saturated with hydrogen. 



Conversely, this intluence itself will be modified by the nature of 

 the groups in the ketone and this the more so as the character of 

 that grou|) differs more from that of the hydrogen atoms. In fact, 

 MoNTAGNK has fouud that the aminobenzophenones are absolutely not 

 affected by strong alcoholic potassium hydroxide. 



3. This influence of the substituents on the stability of the central 

 piuacoue-C — C bond in regard to alkalis can now be readily deduced 

 from our measurements (see graphic representation .1 and 7iand table). 



If we take the ordinary benzpinacone as the starting point, it 

 appears that the methyl- (9 and 8) and the methoxylgroup (7) in the 

 para-position lender the molecule stable, on the other hand the 

 halogen atoms will render the said bond looser and this in the order 

 para (4), ortho (2), meta (table N". 3). The para-placed bromine atom 

 (5) joins the chlorine atom ; also in the pinacone from 4.4' dichloro- 

 benzophenone (6) the bond is considerably looser than in the pinacone 

 from 4 chlorobenzophenone. 



Whereas in the pinacone from 2 CI 4'-methylbenzophenone the two 

 iiilluences, as might be expecte(l,couuteract each other (10) it ajjpears that 

 in the pinacone from 4 CI 4'-methyli)enz()|ihen()ne (11) the methylgroup 

 unexpectedly promotes the loosening action of the chlorine atom. 



The method followed bv us thus indicates the wav to iiiutiiallv 



1) MoNTAüNE, Recucil 27, 'A'll (1908). 



MoüTAGNE anil Moll van Ciiarentk, H. 31, 298 (1012). 



-) We may also express lliis; as follows : Iho oxygen aclivalcd by tlio alkali 

 metal v»'ilhdra\vs tlie hydrogen IVom llie alcohol molecules. 



